Preservative free insulin formulations and systems and methods for aerosolizing

ABSTRACT

One embodiment describes an insulin formulation that is specifically adapted for aerosolization. The formulation comprises a major amount of water and a minor amount of insulin. Further, the formulation is preservative free, without meta-cresol, cresol or phenol, to permit the formulation to be aerosolized using a vibrating aperture plate without substantial foaming of the insulin formulation.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation in part application and claims thebenefit of U.S. Provisional Application No. 61/335,769, filed on Jan.12, 2010, the complete disclosure of which is herein incorporated byreference.

This application is also related to copending U.S. application Ser. No.______, entitled “PRESERVATIVE-FREE SINGLE DOSE INHALER SYSTEMS” andfiled on the same date as the present application, the completedisclosure of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

This application relates generally to the field of insulin formulations,and in particular to insulin formulations that can be aerosolized usingan aerosolizer that vibrates a mesh at high frequencies.

A variety of insulin formulations have been widely available for years.These formulations are primarily engineered to have a long shelf lifeand are typically administered by injection. This application relates toinsulin formulations that are particularly suited for delivery byinhalation as an aerosolized spray.

BRIEF SUMMARY OF THE INVENTION

In one embodiment, an insulin formulation is provided that isspecifically adapted for aerosolization. The formulation comprises amajor amount of water and a minor amount of insulin. Further, theformulation is preservative free to permit the formulation to beaerosolized using a vibrating aperture plate without substantial foamingof the insulin formulation. For example, the formulation does notinclude meta-cresol, cresol, phenol or the like.

In one aspect, the insulin has a concentration of about 100 IU/ml toabout 1200 IU/ml, and more preferably from about 200 IU/ml to about 800IU/ml of human insulin. Also, the water may comprise in volume about99.8% to about 97.0%, and the human insulin may comprise in volume about0.2% to about 3.0%.

In another embodiment, an insulin formulation is provided that isspecifically adapted for aerosolization. The formulation consistsessentially of a major amount of water and minor amounts of insulin,HCl, and NaOH. The formulation is preservative free such that theformulation may be aerosolized using a vibrating aperture plate withoutsubstantial foaming of the formulation.

In one aspect, the insulin has a concentration of about 100 IU/ml toabout 1200 IU/ml, and more preferably from about 200 IU/ml to about 800IU/ml of human insulin. Also, the water may comprise in volume about99.8% to about 97.0%, the human insulin comprises in volume about 0.2%to about 3.0%.

In still another embodiment, the invention provides an insulinformulation specifically adapted for aerosolization that comprises amajor amount of water and a minor amount of insulin. The formulation iscapable of being aerosolized as a spray using a vibrating aperture platehaving a plurality of apertures that vibrates at a frequency in therange from about 50 kHz to about 150 kHz. Also, the amount of theinsulin formulation has a volume of up to about 200 uL, and the time toaerosolize 97% is less than about 22 seconds.

In a particular aspect, the insulin formulation does not contain apreservative such that the formulation may be aerosolized using thevibrating aperture plate without substantial foaming of the formulation.Further, the insulin may have a concentration of about 100 IU/ml toabout 1200 IU/ml, and more preferably from about 200 IU/ml to about 800IU/ml of human insulin.

The invention in one embodiment also provides an exemplary method foraerosolizing an insulin formulation. The method includes the use of aninsulin formulation comprising a major amount of water and minor amountsof insulin, HCl and NaOH. An amount of the insulin formulation issupplied to a rear side of an aperture plate having a plurality ofapertures. The aperture plate is vibrated while the insulin formulationis at the rear side. Vibration causes the supplied insulin to be ejectedfrom a front side of the aperture plate as an aerosolized spray withoutsubstantial foaming of the insulin formulation.

In one step, at least about 97% of the formulation is ejected. Also, theamount of the insulin formulation has a volume of up to about 100 μL,and the time to aerosolize the at least about 97% is less than about 11seconds. In another aspect, the aperture plate is vibrated with anamplitude that is less than about 4 μm, in some cases less than about 3μm, and in further cases less than about 2 μm. Further, the aerosolizedspray may comprise aerosolized droplets having a mean size in the rangefrom about 3 μm to about 8 μm, and preferably from about 3 μm to about 6μm. In another aspect, the formulation has less than about 3%, in somecases less than about 1%, and more preferably less than about 0.1%converted to foam when vibrating the aperture plate.

In a certain aspect, the insulin has a concentration of about 200 IU/mlto about 800 IU/ml of human insulin. Also, the aperture plate may have adiameter in the range from about 5 mm to about 8 mm, with apertureshaving a size in the range from about 3 μm to about 8 μm, a thickness inthe range from about 50 microns to about 70 microns, and is vibrated ata frequency in the range from about 50 kHz to about 150 kHz.

In still a further embodiment, the invention provides an aerosolizationsystem that comprises an inhaler comprising a housing defining amouthpiece, and an aerosol generator disposed in the housing. Theaerosol generator comprises a vibratable membrane having a front faceand a rear face, and a vibratable element used to vibrate the membrane.The system further includes a container containing a volume of aninsulin formulation consisting essentially of a major amount of waterand a minor amount of insulin. The formulation is preservative free suchthat the formulation may be aerosolized using a vibrating aperture platewithout substantial foaming of the formulation.

In one aspect, the insulin has a concentration of about 200 IU/ml toabout 800 IU/ml of human insulin. In a further aspect, the apertureplate has apertures having a size in the range from about 3 μm to about8 μm. Further, the vibratable membrane may be configured to vibrate witha frequency that is less than about 2 μm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective, partial cut-away view of one embodiment of adispensing apparatus according to the invention.

FIG. 2 is a more detailed view of the dispensing apparatus of FIG. 1.

FIG. 3 is a graph illustrating the time required to aerosolize differentinsulin formulations.

FIG. 4 is a graph illustrating aerosolization times for various insulinformulations as well as for water and saline.

FIG. 5 is a graph illustrating aerosolization times for various insulinformulations, including the formulations of Examples 1-3 when glycol isadded.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention provide a preservative free insulinformulation that may be used with an aerosolization device to provide anaerosolized spray of insulin. More specifically, the insulinformulations do not contain any preservatives, including phenol,metacresol, chloro-cresol, thymol and mixtures thereof or the like. Theabsence of such preservatives enable the formulations to be aerosolizedas a liquid spray using a vibrating mesh or aperture plate that operatesat high frequencies. The absence of such preservatives permits a dosageof the formulation to come into contact with the vibrating mesh withoutsubstantial foaming of the formulation. In turn, the formulation may beaerosolized more quickly. Further, substantially all of the liquid isable to be aerosolized.

The formulations contain water in major and human insulin in minoramount. The formulations may also include various concentrations ofhuman insulin. For example, the concentrations may be in the range fromabout 100 IU insulin/ml of formulation to about 1200 IU insulin/ml offormulation, and more preferably from about 200 IU insulin/ml offormulation to about 800 IU insulin/ml of formulation.

In addition to water and human insulin, the formulations may alsoinclude zinc, acetate, chloride and sodium. The zinc ion and acetate ioncome from the drug substance, e.g., the insulin. The chloride ion andsodium ion are added during dissolution of the insulin and adjustment ofthe pH. Merely by way of example, the NaCl concentration may be about 20mM for an 800 IU insulin/ml formulation, about 10 mM for a 400 IUinsulin/ml formulation, and about 5 mM for a 200 IU insulin/mlformulation.

The following are various non-limiting examples of preservative freeformulations that may be used according to the invention:

EXAMPLE 1 800 IU Insulin/ml Formulation

In this example, 50 ml of the 800 IU insulin solution was made bysuspending 1400 mg human insulin (with 2 to 4 Zn²⁺ per insulin hexamer)in 44 ml water, then dissolved the insulin by adding 1.0 ml 1N HCl to pHabout 3.0. After all of the insulin dissolved, 1.6 ml 1N NaOH was slowlyadded to titrate the insulin solution to pH 7.4. Finally, water wasadded to 50 ml.

EXAMPLE 2 400 IU Insulin/ml Formulation

In this second example, 50 ml of the 400 IU insulin solution was made bysuspending 700 mg human insulin (with 2 to 4 Zn² per insulin hexamer) in44 ml water, then dissolved the insulin by adding 0.5 ml 1N HCl to pHabout 3.0. After all of the insulin dissolved, about 0.8 ml 1N NaOH wasslowly added to titrate the insulin solution to pH 7.4. Finally, waterwas added to 50 ml.

EXAMPLE 3 200 IU Insulin/ml Formulation

In this third example, 50 ml of the 200 IU insulin solution was made bysuspending 350 mg human insulin (with 2 to 4 Zn²⁺ per insulin hexamer)in 44 ml water, then dissolved the insulin by adding 0.25 ml 1N HCl topH about 3.0. After all of the insulin dissolved, about 0.4 ml 1N NaOHwas slowly added to titrate the insulin solution to pH 7.4. Finally,water was added to 50 ml.

A wide variety of inhalers or aerosolizers may be used to aerosolize thepreservative free solution. For example, an aerosolizing apparatus maycomprise a housing defining a dispensing outlet, a vibratable membranehaving a front face exposed at the outlet and a rear face for receivinga liquid to be dispensed, and a vibrating mechanism connected to thehousing and operable to vibrate the membrane to dispense aerosol of theliquid through the membrane. In some cases, a liquid delivery system mayalso be used to deliver a metered quantity of the liquid from to therear face of the membrane. In this way, a metered quantity of liquid isdispensable at the outlet by operating the vibrating mechanism for anoperating period sufficient to completely aerosolize the meteredquantity of the rear face.

Examples of certain types of aerosolizers that may be used are describedin copending U.S. application Ser. No. ______, entitled“PRESERVATIVE-FREE SINGLE DOSE INHALER SYSTEMS” and filed on the samedate as the present application, previously incorporated by reference.

Referring now to FIG. 1, one embodiment of an inhaler will be described.FIG. 1 illustrates a partially cut-away view of an inhaler 100. Inhaler100 may be used in connection with various containers that supply theliquid insulin. For example, inhaler 100 may be used with a unit doseblister package for supplying a metered quantity of insulin to theinhaler. Inhaler 100 comprises two subassemblies 102 and 112. The firstsubassembly 102 defines a compartment for the electronic circuitry andthe batteries, and the second subassembly 112 defines a housing with adispensing outlet 105 and contains a vibratable membrane aerosolgenerator 108 and a lid 104 that may be closed as shown by arrow 115.Aerosol generator 108 has a front face exposed at the outlet duct 111and a rear face 109 contacted in use by liquid to be dispensed. Aerosolgenerator 108 is connected to the housing of subassembly 112 and isoperable to dispense the active pharmaceutical agent as an aerosolthrough the mouthpiece 105. Exemplary aerosol generators that may beused are also described in U.S. Pat. Nos. 5,164,740; 6,629,646;6,926,208; 7,108,197; 5,938,117; 6,540,153; 6,540,154; 7,040,549;6,921,020; 7,083,112; 7,628,339; 5,586,550; 5,758,637; 6,085,740;6,467,476; 6,640,804; 7,174,888; 6,014,970; 6,205,999; 6,755,189;6,427,682; 6,814,071; 7,066,398; 6,978,941; 7,100,600; 7,032,590;7,195,011, incorporated herein by reference. These references describeexemplary aerosol generators, ways to manufacture such aerosolgenerators and ways to supply liquid to aerosol generators, and areincorporated by reference for at least these features. The aerosolgenerators may comprise vibratable membranes having tapered aperturewith a size in the range from about 3 μm to about 8 μm, preferably fromabout 3 μm to about 6 μm, and in some cases around 4 μm. The membranemay be domed shaped and be vibrated by an annular piezoelectric elementthat circumscribes the apertures. The diameter of the membrane may be inthe range from about 5 mm to about 8 mm. The membrane may also have athickness in the range from about 50 microns to about 70 microns.Typically, the membrane will be vibrated at a frequency in the rangefrom about 50 kHz to about 150 kHz.

Further, to minimize foaming of the insulin formulations, the membranemay be vibrated at an amplitude that is less than about 4 μm, preferablyless than 3 μm and more preferably less than 2 μm.

Each time a metered quantity of liquid is supplied to inhaler 100, it isdelivered to the rear face 109 of the aerosol generator. Hence, for eachuse a metered quantity of aerosolized pharmaceutical agent may bedispensed at the mouthpiece outlet 105 by operation of the aerosolgenerator.

Inhaler 100 further includes a well 107 to receive the content of acontainer so that it may be supplied to the aerosol generator 108. Thewell 107 has a concave shape and defines a fluid passage to thevibrating aerosol generator 108.

FIG. 2 illustrates the vibrating membrane 109 of the aerosol generator108 in greater detail. When a volume of liquid is dispensed an indicatorlight 120 starts to blink signaling to the patient that the inhaler 100is ready for use. At any time shortly thereafter the patient may inhalethrough the mouthpiece 105. Patient inhalation is detected by a flowsensor which in turn activates the aerosol generator 108 to produceaerosol particles into the duct 111. Aerosol is entrained in theinhalation air flow in the direction shown by arrows 121 and flow viathe respiratory system to the lungs of the patient. When the entire doseis aerosolized, which may take one or morel breaths, the “end-of-dose”indicator light 121 lights a second time to signal the patient that theentire dose has been delivered. Delivery of the entire dose is obtainedwhen at least about 95% of the dose is delivered, more preferably 98%and most preferably when more than 99% of the dose is delivered. In oneembodiment, the opening funnel to the aerosol generator is sufficientlylarge such that the liquid delivery to the aerosol generator isdelivered in its entirety. To receive the dose, the patient may takeseveral inhalations or a single inhalation depending on the volumedelivered to the mesh and the patient's breathing capacity. Eachinhalation should be a deep breath to assure that the aerosol reachesdeeply to the lungs.

The preservative-free insulin formulations are particularly useful inthat they do not have substantial foaming when coming into contact withthe vibrating membrane. In turn, this permits the formulation to berapidly aerosolized. This is a critical feature in that the dosage needsto be quickly aerosolized so that the user can inhale the insulin in ashort time frame. In most cases, it is desirable to limit the number ofinhalations required to administer the formulation. Depending on theuser's ability to inhale, it is desirable to administer the entiredosage in about 1 to 3 breaths. Typical dosage amounts are in the rangefrom about 40 μL to about 200 μL. Aerosolizing these volumes fast enoughto permit them to be inhaled within a few breaths is a critical featureof the invention. It is desirable to aerosolize these volumes in lessthan about 22 seconds, and more particularly less than about 15 secondsto permit them to be inhaled in about 1 to 3 breaths.

The graphs of FIGS. 3 and 4 illustrate how the insulin formulations ofthe invention provide this critical feature while commercially availableinsulin formulations are unable to aerosolize in an acceptable timeframe. As shown, the Humalin, Lantus and Humalog formulations took inexcess of 30 seconds to aerosolize 100 μL of insulin formulation. Thisis because both of these formulations had significant foaming thatprevented the formulation from being ejected as liquid droplets from thefront face of the vibrating membrane. Further, with the Lantusformulation, 6.9 μL remained at the end of the test. Preferably,substantially all the liquid will be aerosolized, and typically lessthan about 3 μL will remain, corresponding to an aerosolizationefficiency of at least about 97% aerosolization.

In contrast to the insulin formulations that contain preservatives, theinsulin formulations of the invention (with concentrations of 200 IU,400 IU and 800 IU, corresponding to Examples 3, 2, and 1, respectively)were each aerosolized in about 10 seconds. With less than 3 ul offormulation remaining, more than about 97% of the formulation wasaerosolized. By aerosolizing this volume in around 10 seconds, mostindividuals, including children, are able to inhale the complete dosagein around 1 to 3 breaths. The insulation formulations of the inventionwere able to aerosolize at essentially the same rate as water and asaline solution.

One significant reason for the foaming is due to the preservative usedin the formulation. For example, many formulations contain thepreservative meta-cresol at 2.5-3.15 mgs/ml. However this additive wasfound to have no effect on foaming FIG. 4. Thus, eliminating suchpreservatives substantially eliminates foaming and markedly increasesaerosolization times.

As one specific example, each milliliter of HUMALOG contains 100 iulispro, 16 mg glycerin, 1.88 mg dibasic sodium phosphate, 3.15 mgmeta-cresol, zinc oxide content adjusted to provide 0.0197 mg zinc ion,trace amounts of phenol, and water for injection. Insulin lispro has apH of 7.0-7.8, and hydrochloric acid (10%) and/or sodium hydroxide (10%)may be added to adjust pH.

As another example, LANTUS consists of insulin glargine dissolved in aclear aqueous fluid. Each milliliter of LANTUS (insulin glargineinjection) contains 100 IU (3.6378 mg) insulin glargine. Inactiveingredients for the 10 mL vial are 30 mcg zinc, 2.7 mg m-cresol, 20 mgglycerol 85%, 20 mcg polysorbate 20, and water for injection. Inactiveingredients for the 3 mL cartridge are 30 mcg zinc, 2.7 mg m-cresol, 20mg glycerol 85%, and water for injection. The pH is adjusted by additionof aqueous solutions of hydrochloric acid and sodium hydroxide. LANTUShas a pH of approximately 4.

Further, each milliliter of Humulin contains 500 IU of human insulin, 16mg glycerin, 2.5 mg meta-cresol as a preservative, and zinc-oxidecalculated to supplement endogenous zinc to obtain a total zinc contentof 0.017 mg/100 units. Sodium hydroxide and/or hydrochloric acid may beadded during manufacture to adjust pH.

As yet another example, Humalin R formulation is 100 IU recombinanthuman insulin, 16 mg (174 mM) glycerin, 2.5 mg metacresol (22.7 mM,0.25%), HCl and NaOH.

Finally Novolin R formulation is 100 IU recombinant human insulin,glycerin, metacresol, HCl and NaOH.

Other formulations containing preservatives are described in U.S. Pat.Nos. 6,489,292 and 6,211,144, incorporated herein by reference. Suchpreservatives can include phenol, m-cresol, chloro-cresol, thymol andmixtures thereof. Some similar non-phenol preservatives include bi- ortricyclic aliphatic alcohols and purines, such as a bicyclic aliphaticalcohol, including a monoterpenol, such as isopinocampheol,2,3-pinandiol, myrtanol, borneol, norborneol or fenchol, a tricyclicaliphatic alcohol, such as 1-adamantanol, and a purine, such as adenine,guanine or hypoxanthine. As described in these patents, suchpreservatives are included to ensure stability of the insulin. However,the preservatives included in the formulations described in thesepatents cause the formulations to foam when subjected to vibratingaperture plates, significantly increasing the time to aerosolize.

The formulations of the invention do not contain such preservatives orstabilizers. As such, little or no foaming occurs, allowingsubstantially all of the aerosol generator to rapidly aerosolize theformulations.

Some insulin formulations also include surfactants or detergents. Thesealso can cause foaming in the presence of a vibrating aperture plate ormesh. The formulations of the invention also avoid the use of suchsurfactants or detergents.

While the formulations of the invention lack the use of preservatives,the integrity of the formulations can still be maintained by properpackaging and management of shelf life. In this way, the formulationsmay be preservative free and still commercially viable.

FIG. 5 illustrates what happens when 20 μL glycol added per 100 IU (1ml) was added to the formulations of Examples 1-3. These were thencompared to Humalin, Lantus and Humalog, saline and water examples ofFIG. 4. As shown, inclusion of glycol had essentially no effect on theaerosolization times of Examples 1-3, confirming that glycol does notcontribute to foaming, with the main contributor of foaming being thepreservatives as previously described.

The invention has now been described in detail for purposes of clarityand understanding. However, it will be appreciated that certain changesand modifications may be practiced within the scope of the appendedclaims.

1. An insulin formulation specifically adapted for aerosolization, theformulation comprising: a major amount of water; a minor amount ofinsulin; wherein the formulation is preservative free to permit theformulation to be aerosolized using a vibrating aperture plate withoutsubstantial foaming of the insulin formulation.
 2. An insulinformulation as in claim 1, wherein the insulin has a concentration ofabout 100 IU/ml to about 1200 IU/ml of human insulin.
 3. An insulinformulation as in claim 1, wherein the water comprises in volume about99.8% to about 97.0%, and the human insulin comprises in volume about0.2% to about 3.0%.
 4. An insulin formulation as in claim 1, wherein theformulation does not include meta-cresol, cresol or phenol.
 5. Aninsulin formulation specifically adapted for aerosolization, theformulation consisting essentially of: a major amount of water; a minoramount of insulin; a minor amount of HCl; and a minor amount of NaOH;wherein the formulation is preservative free such that the formulationmay be aerosolized using a vibrating aperture plate without substantialfoaming of the formulation.
 6. An insulin formulation as in claim 5,wherein the insulin has a concentration of about 100 IU/ml to about 1200IU/ml of human insulin.
 7. An insulin formulation as in claim 5, whereinthe water comprises in volume about 99.8% to about 970%, the humaninsulin comprises in volume about 0.2% to about 3.0%.
 8. An insulinformulation specifically adapted for aerosolization, the formulationcomprising: a major amount of water; a minor amount of insulin; whereinthe formulation is capable of being aerosolized as a spray using avibrating aperture plate having a plurality of apertures that vibratesat a frequency in the range from about 50 kHz to about 150 kHz, andwherein the amount of the insulin formulation has a volume of up toabout 200 μL, and wherein the time to aerosolize the 97% is less thanabout 22 seconds.
 9. An insulin formulation as in claim 8, wherein theinsulin formulation does not contain a preservative such that theformulation may be aerosolized using the vibrating aperture platewithout substantial foaming of the formulation.
 10. An insulinformulation as in claim 8, wherein the insulin has a concentration ofabout 100 IU/ml to about 1200 IU/ml of human insulin.
 11. A method foraerosolizing an insulin formulation, the method comprising: providing aninsulin formulation comprising a major amount of water, and minoramounts of insulin, HCl and NaOH; supplying an amount of the insulinformulation to a rear side of an aperture plate having a plurality ofapertures; vibrating the aperture plate while the insulin formulation isat the rear side, wherein vibration causes the supplied insulin to beejected from a front side of the aperture plate as an aerosolized spraywithout substantial foaming of the insulin formulation.
 12. A method asin claim 11, wherein at least about 97% of the formulation is ejected.13. A method as in claim 12, wherein the amount of the insulinformulation has a volume of up to about 100 μL, and wherein the time toaerosolize to at least about 97% is less than about 11 seconds.
 14. Amethod as in claim 11, further comprising vibrating the aperture platewith an amplitude that is less than about 2 μm.
 15. A method as in claim11, wherein the aerosolized spray comprises aerosolized droplets havinga mean size in the range from about 3 μm to about 8 μm.
 16. A method asin claim 11, wherein the formulation has less than about 3% converted tofoam when vibrating the aperture plate.
 17. A method as in claim 11,wherein the insulin has a concentration of about 100 IU/ml to about 1200IU/ml of human insulin.
 18. A method as in claim 11, wherein theaperture plate has apertures having a size in the range from about 3 μmto 8 μm, and is vibrated at a frequency in the range from about 50 kHzto about 150 kHz.
 19. An aerosolization system, comprising: an inhalercomprising a housing defining a mouthpiece, an aerosol generatordisposed in the housing, wherein the aerosol generator comprises avibratable membrane having a front face and a rear face, and avibratable element used to vibrate the membrane; a container containinga volume of an insulin formulation consisting essentially of a majoramount of water and a minor amount of insulin, wherein the formulationis preservative free such that the formulation may be aerosolized usinga vibrating aperture plate without substantial foaming of theformulation.
 20. A system as in claim 20, wherein the insulin has aconcentration of about 100 IU/ml to about 1200 IU/ml of human insulin.21. A system as in claim 20, wherein the aperture plate has apertureshaving a size in the range from about 3 μm to 8 μm.
 22. A system as inclaim 20, wherein the vibratable membrane is configured to vibrate witha frequency that is less than about 2 μm.